If you haven’t seen it by now, Finish Line has a new tubeless tire sealant. Far from just another tire sealant, Finish Line claims that theirs is revolutionary. Why? They say it will never dry out, it will last the life of your tire, and it cleans up easily with water among other benefits.

While the press release offered the basic details, we thought that this product was worthy of a more in depth look.

Bikerumor: Why hasn’t anyone done this with a sealant before? Or maybe it should be framed as, what were the biggest hurdles to overcome in creating a long lasting sealant?

Dave Vollbach, Finish Line Marketing Manager: To be frank, Latex sealants work well and have been accepted as an industry standard for a long time. Many users of latex sealants, however, are well aware of latex’ short comings.  Developing a non-latex formulation that uses fibers was challenging.  The most significant challenge was choosing the type of fibers (we use 5 different types) and the length, shape and diameter of those fibers- these are all specifications that we control. The second challenge was finding a way to keep these fibers, each with different densities, suspended in a carrier. If there was separation in the bottle or inside the tire, the sealant would not work.

Bikerumor: You mention you worked with Multi-Seal – is this a new formulation specifically for Finish Line, or a previous formula used in other industries?

Finish Line: Finish Line has enjoyed an almost 30 year working relationship with DuPont. Our founder, Hank Krause, works closely with scientists and engineers at Dupont’s Research Center in Wilmington, Delaware.  When we started our work using Dupont Kevlar® fibers, Dupont suggested that we consult with Multi Seal, who was already using Kevlar® in industrial and military tire sealants.  Our collaboration with Multi Seal led to a bicycle-specific formulation that is both extraordinary and much different than the sealants used in their heavy-duty industrial tires.

Bikerumor: What causes some sealants to weep through the sidewall of certain tires? Will that happen with Finish Line?

Finish Line: Two part answer: 1. When a new tire is installed using latex, it is common for the latex to spit and splatter through the bead when inflated and spun.  This creates a bit of a mess and leads to the loss of some sealant. Finish Line’s fiber technology dramatically reduces and even eliminates this phenomena. 2: Some tires, especially some of higher end ones, have exceptionally thin sidewalls. And of course rubber is porous.  Over time, small amounts of sealant, latex and ours, will soak into the rubber, and to this extent, this help reduce loss of air due to rubber porosity. Our testing shows that tires treated with our sealant lose less air over time than do latex treated tires.  We are not sure if this is due to tighter seals around the beads, or less loss of air through the rubber.

Bikerumor: Does Finish Line sealant need to be installed in a new tire? Will it react with other sealants?

Finish Line: We definitely do not recommend mixing sealants. Since our sealant works via a fundamentally different mechanism than latex sealants, mixing our sealant with any other sealant will reduce effectiveness. Therefore, when converting from a latex sealant to Finish Line, it is important to remove as much of the old as possible.

Bikerumor: Can you transfer Finish Line sealant from one tire to another? Say if you wanted to change tires for conditions?

Finish Line: Since our sealant will last the useful life of the tire, it can be re-used or transferred from one tire to another. That said, because of the absorption noted above and a general inability to transfer every last bit of the sealant, we would recommend adding a bit more sealant to the new tire.

Bikerumor: If it can be used to -10°F, it seems like a good candidate for many fat bike users – what amount of sealant would you recommend for 4″ tires? 5″ tires?

Finish Line: We would recommend 6-8oz in a 4” tire and at least 8oz in a 5” tire. I would say that if an end user is in doubt about dosage, adding a little more for safety won’t be a problem. I should also note that while our sealant won’t freeze down to -10º F, it will flow more slowly as the temperature drops well below freezing. It will still work, but because of the reduced flow rate punctures may take a few extra seconds to seal.

Bikerumor: Can Finish Line Sealant be installed through the valves? Or is it best to open the tire up and dump it in?

Finish Line:  Finish Line Sealant can definitely go through valves, and our tip actually fits perfectly over a presta valve when you snip it off about halfway down (This is on directions of label). As an additional bonus, since our sealant isn’t an adhesive, your valve cores won’t get gunked up/clogged like they always do with other sealants. If you’ve ever tried to pump up a tire that had sealant installed through the valve stem months before, you know what I’m talking about.

*updated at 12:30 EST with more info from Finish Line



  1. Stefan Roussev on

    How environment friendly and safe for your health is this solution with possibly using carbon fibers in it? You don’t want to inhale a carbon fiber fine dust in your lungs.

      • TheKaiser on

        That it is just Kevlar is unclear to me. The interview above says “The most significant challenge was choosing the type of fibers (we use 5 different types) and the length, shape and diameter of those fibers”. You could read that as 5 different types of Kevlar, or Kevlar plus some other materials.

        As Stefan said, what are the health effects of inhaling them? I think most shop employees have a story of 2 of a tubeless tire blowing off the rim when seating it, and the ensuing explosion both deafening them and covering them with sealant mist and droplets. Similarly, when riding, if a front wheel puncture doesn’t seal instantly, riders often get spray off the wheel that would again be small respireable droplets.

        @Pynchonite, your question about environmental build up of microplastics and how kevlar relates to that is a good one. While every little bit helps, all of us disk brake riders are also spreading kevlar around if we aren’t using sintered metallic pads. Even if we are using sintered pads, we’re spreading those metals, and rim brake riders are spreading their rubber dust too, so this isn’t totally new.

        • JNH on

          Aramids are plastics, they don’t biodegrade so they’re as bad as all other plastics in that regard. They are however a lot safer than what they replaced in industrial use, which was Asbestos.

        • Pynchonite on

          That’s an excellent point. If you’ve ever cleaned a rim or a brake caliper, you can see and feel some of that dust, and undoubtedly much of it enters the local hydrosphere. So there is a lot that we need to know about how our sport affects the world.

          In the case of a new product such as this, there is the question of whether it makes more or less of an impact than the old, particularly since there is a known similar danger. Working in a shop, I can confidently say that many of these fibers will end up at some point in the local water system. If the sealant lasts the life of the tire, then some will get poured down a drain or emptied into a garbage can once the tire is changed. Or, as you mentioned with regard to the other question, sprayed onto the local trail while sealing a puncture. Anyway, I would like to hear from Finish Line about whether the water issue is one that they’ve encountered or addressed.

        • Hank Krause on

          While some have raised concerns about Kevlar® Fibers’ effect on the environment, and similarities to plastic microbeads; comparing microbeads to Kevlar fiber is not an accurate analogy. While both are resistant to bio-degradation, many types of microbeads can pass through water filtration systems used in municipalities. Kevlar® fibers would not pass through these filters, they are too large. As such, microbeads have the ability to make their way into the food chain where a process of biomagnification begins, Kevlar fibers can not. Additionally, many microbeads contain harmful chemicals, while Kevlar® fiber is inert and non-toxic. The liquid portion of Finish Line sealant is non-toxic and 100% readily biodegradable. I hope this helps!

    • Pynchonite on

      I had the same question, except with regards to Kevlar fibers infiltrating water sources. Microscopic plastic particulates have been shown to be immensely harmful to animals up to and including humans. How are the Kevlar fibers safer? Are they?

      • Padrote on

        It’s not an unreasonable question, but in an industry (world?) already flush with environmentally unfriendly substances and manufacturing processes, it’s hard to get riled about 8 ounces of this stuff lost once a year. For my time and money there are much bigger problems to focus on.

  2. Mike Williams on

    +1 for the last point if it is true. The Latex sealant I currently use has caused all sorts of problems with Presta valves this winter (it was OK during the summer). Not only can it make the tire harder to inflate it can also make the valve harder to close all the way (especially if you are wearing gloves) and I have had a few slow leaks that turned into flats. I now pull the valves and clean them after adding sealant and a few rides. Hope to get some long term user reviews of this FL product before I use up my S%^&s (or buy new tires).

      • Mike Williams on

        I have to inject the sealant because breaking the bead on my tubeless optimized rims is a real pain (I have to lay the wheel down on a soft surface, stand on the tire with both heels and my 180lbs till it breaks, work my way around, and then repeat on the other side). It is probably related to the lower temperatures since it didn’t happen during the warmer weather. I want a better solution.

      • Mike Williams on

        Nah…I’d just rather have a better sealant. I can easily clean my current ones (for $0)…I just don’t want to have to do it.

  3. Flatbiller on

    “Our testing shows that tires treated with our sealant lose less air over time than do latex treated tires. We are not sure if this is due to tighter seals around the beads, or less loss of air through the rubber.”

    So they tested, which I assume means in a lab with precise, scientific tools, and are not sure about this seemingly measurable phenomenon?

  4. Woody on

    I wonder how this would work in road tubeless. Yet to find a good one that works well at 75-100psi. Article says MTB sealant but the product does not differentiate. In fact their utube video shows a road tubeless tire getting stabbed.

    • TheKaiser on

      Maybe you have already tried it, but I hear all the road tubeless guys saying the Orange Seal is the best they’ve tried for high pressure applications.

  5. Drew (@IrrelevantD) on

    “As an additional bonus, since our sealant isn’t an adhesive, your valve cores won’t get gunked up/clogged like they always do with other sealants.”

    The use of the word ‘always’ kinda annoys me. I currently use Stan’s Race day, I install it through the valve even though Stan’s themselves say not to, my valves do NOT get “gunked up”. While I’m intrigued by the product, this one comment makes me not want to try it.

  6. MsC on

    “It cleans up easily with water among other benefits.” In case your clothes get stained due to a spray of sealant when puncturing, does it wash off or will it leave permanent yellow stains like many of the other sealants?

  7. O. Tan on

    Hmm, packaging makes no mention for Road or MTB, so I guess it works on both? If this works as advertised, I’ll likely switch to tubeless once my current tire wears out.

  8. Joseph W. on

    This is the same thing we use in tractor tires. There’s nothing new about this product but the company using it & the label on it. Go to the hardware store & get tractor tire sealant. It has 3-5 kinds of bits in it from cotton to rubber pieces & Kevlar! Same thing. Non latex…water clean up.. doesn’t dry out unless exposed to air. Comes in red or blue. It’s the same thing. Don’t be scammed by so called new technologies. I’ve used tractor sealant for years. I use mine in tubes & have the same tubes for over 1.5 years. I ride Conti tires with WTB team rim on a carbon frame. Don’t be fooled…tractor sealant is $10-$15 for a hug bottle.

    • dockboy on

      Your tubes last a year and a half and that’s a good thing? Your claim that this is tractor sealant may be correct, but your tubes longevity doesn’t inspire confidence.
      How do you know this is the same thing?

    • Alex Barouh on

      Hi Joseph,

      You might have used Multi Seal’s tractor tire sealant in the past but Finish Line’s tubeless tire sealant is designed from the ground up to be a completely different formula. The tractor sealant would be far too thick and viscous to effectively seal bicycle tires. If you compare the two you’ll notice the viscosity of your tractor sealant is much thicker when compared Finish Line’s sealant which is much lighter. This is not a repackaged product but something completely new and unique.

      Alex Barouh
      Finish Line Technologies

  9. Ryan on

    Wow, I had no idea that tubeless was so difficult and technical. I pour a couple ounces of whatever I have on hand into a tire and forget about it until I happen to notice that the tire isn’t holding pressure as well as it used to. Then I just do it all over again. What am I doing wrong here…?

  10. jimbo on

    ok. im trying this out (ordered), but having seen how much air filters through the rubber on my maxxis and schwalbe tyres this drying out issue is not good (still claims on the finishline website that it doesnt dry out..conned?) anyways. could adding water now and again help prevent this? would it mix ok or stay separated?

    btw i just got a cst rockhawk tyre (same parent company as maxxis)..and bloody hell. mounted to a stans flow mk3 rim with a handpump..not one little leak while inflating..aired straight up…its got no sealant in and has held pressure for two weeks. and at about 30-40% of the cost.
    im very much done with maxxis and its mass advertised shoddy products. ..schwalbe…..shame on you.


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